1. Field of the Invention
The invention pertains to pool cleaning equipment. More particularly it pertains to an accessory for a pool cleaning device operated by the suction of the pool's circulation system.
2. Description of the Prior Art
A swimming pool water circulation system includes the pool itself, a motor driven pump, a flow duct from the pool to the inlet or suction side of the pump, a return flow duct from the discharge or pressure side of the pump to the pool, and a system filter unit in the return flow duct. If desired, a water heater can be installed in the return duct. The system filter is of the kind which removes sand, dust and other finely divided solid matter from water passed through it; many system filters use a diatomaceous earth filtering medium. System filters are not well suited for the removal from water of larger things such as leaves, flower petals, pine needles and the like. Therefore, it is now common to equip swimming pools with skimmers for the removal from water entering the return flow duct to the pump of leaves and the like, which things often float on the surface of the pool.
A typical skimmer, according to prevailing design philosophy, defines a vertically elongate chamber which has a lower basket portion, a central plenum portion, and an upper chimney portion which is closed by a removable cover. A foraminous basket, having a selected pore size, is supported across the top of the basket cavity so the bottom of the basket is above the bottom of the cavity. A throat extends laterally from the plenum to a principal inlet opening to the skimmer; that opening is square or rectangular and is defined in a vertical plane. A coupling for a flow pipe, and often two such couplings, is located at the bottom of the basket cavity of the skimmer. The skimmer is built into the pool so that the throat inlet opening is centered at the optimum water level in the pool, which level normally varies one to two inches or so above and below the optimum level; the opening is sufficiently high to encompass this range of water levels. The cover for the skimmer chimney is placed flush with a deck or other surface around the pool. The throat is partially submerged if the pool is properly filled, and so the skimmer basket cavity and the lower part of the plenum are filled with water when the pool is filled. A buoyant weir plate, having a pivotal connection at its bottom to the inlet throat, often is mounted across the throat to cause only water immediately at and below the pool surface to flow over the weir and into the skimmer plenum.
The flow duct from the pool to the suction side of the pool circulation pump is connected to the bottom of the basket cavity. When the pump is operated, it takes in water from the skimmer. The water enters the skimmer from the pool through the throat, carrying with it leaves and the like which float on the water surface in the vicinity of the throat opening. Water entering the skimmer via the throat passes through the basket where the leaves and other large things are strained out by the basket. Thus, water passing to the pump is free of large pieces of debris, and the filter is better able to do for a longer period the task assigned to the filter. Debris collected in the skimmer basket is easily dealt with by removing the skimmer cover, removing the basket via the chimney, emptying the basket of collected debris, and replacing the basket.
Pool cleaning devices which operate on pump suction are also known; they include vacuum heads which are coupled to long poles and are moved manually across the pool bottom, and they also include automatic devices which move across the pool bottom--the former are used for short periods, whereas the latter can be operated for long periods measured in hours or days. Such devices are coupled by flexible suction hoses to the circulation pump inlet via the pool skimmer; they operate to suck from the pool bottom accumulations of dirt, leaves and the like, and to introduce them to the pool filter for removal there.
As noted, suction pool cleaners are operated by connection to the suction-side of a pool circulation pump by connection of a suction hose to the pool skimmer. The suction hoses commonly used, while flexible, are not readily bent sharply at right angles. Therefore, such hoses often are coupled to the pool-to-pump return line via the skimmer through the top of the skimmer, i. e., through the skimmer chimney upon removal of the chimney cover. In other instances, the suction hose can be connected to the pool-to-pump suction line through the skimmer throat. Such connections are made either after removal of the skimmer basket (in which case the coarse straining function of the basket is lost) or to special connections inside the skimmer which preserve the function of the basket. In other instances, the hose may be connected to a special port defined adjacent the skimmer throat opening in a side wall of the pool. This can be done where a specially designed skimmer has been built into the pool. However, very few pool skimmers having such special hose connection features now exist.
In equipment where the skimmer basket is removed to connect the suction hose, or where there is a hose port which bypasses the basket, the coarse straining function is lost while the cleaning apparatus is in use. To solve this problem, a product known as a leaf trap is available. This product is configured to fit in-line in the hose between the cleaning implement and the suction port and duplicates the function of the skimmer basket. A perforated basket or a mesh bag having an annular flange is held in a cylindrical housing which has ports at either end. Water coming through a hose from the cleaning implement passes through the intake port into the basket or bag for capture of entrained debris by the basket or bag before the water then flows through the outlet to the suction port. The leaf trap may have neutral buoyancy, or approximately so.
Even with the use of a leaf trap, a number of problems are presented by the use of suction powered pool cleaning apparatus. A primary function of the cleaning is to remove accumulations of dust, sand, fine pebbles etc. from the pool bottom. Accordingly, during the cleaning, large amounts of particulate matter of a size smaller than the mesh of the leaf trap basket or bag will be introduced to the system filter. This will tend to shorten the life of the system filter medium which is often difficult to replace or to clean, as by back washing. The types of particles that settle to the pool bottom are typically larger than the suspended particles that the system filter normally addresses, thus exacerbating the situation. This may be especially significant in areas that are naturally dusty or subject to particulate pollution from industrial or vehicular sources. There may be special situations where large amounts of such material as sand and small pebbles are introduced to the pool by a sandstorm or by being tracked in by individuals.